The present invention relates to an E-plane waveguide circulator having a high-reducing branching region, in which a ferrite body extending through a magnetic field is arranged.
Such E-plane waveguide circulators are disclosed for example in "Microwaves and HF Magazine" Volume 16, No. 2, 1990, pages 168-173. Three waveguide arms of one or two ferrite discs are inserted in the branching region. The thickness of the ferrite disc or discs corresponds only to a fraction of a total height of the branching region. Moreover, the height of the branching region is reduced by insertion of a metal disc on its upper and lower side. The advantage of the E-plane circulator when compared with the H-plane circulator is that at high frequencies an extremely low throughgoing damping is provided. Moreover, the E-plane circulators are of a relative small band (band width of no more than 1%). Moreover, the E-plane circulators which are realized nowadays require large magnets for producing the required magnetization of the ferrite material. At high frequencies, the height of the ferrite discs acts critically on the microwave behavior of the circulator. When an adjustment of the circulator is dispensed with, then for the height of the ferrite discs a tolerance of less than 0.01 MM must be maintained.